Tumour regression after radiotherapy for rectal cancer – Results from the randomised Stockholm III trial. (June 2019)

• Record Type: Journal Article
• Authors: Erlandsson, Johan; Lörinc, Ester; Ahlberg, Madelene; Pettersson, David; Holm, Torbjörn; Glimelius, Bengt; Martling, Anna
• Is Part Of: Radiotherapy and oncology. Volume 135(2019)
• Page Start: 178
• Page End: 186
• Publication Date: 2019-06
• Subjects: Cancer -- Colorectal cancer -- Radiotherapy -- Neoadjuvant treatment -- Neoadjuvant radiotherapy -- Rectal cancer; Oncology -- Periodicals; Radiotherapy -- Periodicals; Tumors -- Periodicals; Medical Oncology -- Periodicals; Neoplasms -- radiotherapy -- Periodicals; Radiotherapy -- Periodicals; Radiothérapie -- Périodiques; Cancérologie -- Périodiques; Tumeurs -- Périodiques; Electronic journals; 616.9940642
• DOI: 10.1016/j.radonc.2019.03.016
• Languages: English
• ISSNs: 0167-8140

Abstract

Highlights: After neoadjuvant radiotherapy in rectal cancer, patients with complete tumour regression or pathology graded complete response have a significantly better survival and fewer recurrences, compared to patients with less tumour response. 5 × 5 Gy with delayed surgery induces more tumour regression and pCR compared to 25 × 2 Gy. Overall treatment time must exceed 4 weeks to achieve pCR after 5 × 5 Gy. Abstract: Background and purpose: Neoadjuvant radiotherapy (RT) in rectal cancer induces tumour regression with a possible complete response (pCR). The optimal fractionation and timing to surgery is not established. The Stockholm III trial randomly assigned 840 patients to 5 × 5 Gy surgery within one week (SRT), 5 × 5 Gy with surgery after 4–8 weeks, and 2 Gy × 25 with surgery after 4–8 weeks (LRT-delay). The aim of this substudy was to assess tumour regression and correlation to survival. Material and methods: All available microscopy slides were assessed by one pathologist, blinded to treatment, regarding tumour regression, graded according to the Dworak system (TRG), TNM-stage and other standard histopathology characteristics. Patients' data were collected from the Swedish ColoRectal Cancer Registry. Outcomes were TRG, pCR-rates, overall survival (OS) and time to recurrence (TTR). Results: 318, 285 and 94 patients were included in the SRT, SRT-delay and LRT-delay groups. Median follow up was 5.7 years. There were significantly lower tumour stages after SRT-delay. pCR was seen in 1 (0.3%), 29 (10.4%) and 2 (2.2%) patients in SRT, SRT-delay and LRT-delay, respectively. The pCR and Dworak grade 4 were associated with superior survival. pCR vs no-pCR Hazard Ratio (95% Confidence Interval) OS: 0.51 (0.26–0.99) p = 0.046, TTR: 0.27 (0.09–0.86) p = 0.027. Conclusion: SRT-delay induces pCR in about 10% of the patients and is in this aspect superior to 25 × 2 Gy. A complete tumour response, TRG 4 using the Dworak system, or a pCR, is associated with superior OS and TTR.